This invention relates generally to cassette tape recorders, and more particularly, the present invention relates to information or music scanning circuitry adapted to such cassette tape recorders.
Nowadays, many cassette tape recorders having a radio has a music scanning function so that a desired piece of music in a music tape can be readily played back. Music scanning, which is also called top-finding, is a function of searching and finding a desired piece of information or music prerecorded in a magnetic recording tape. Namely, the prerecorded information is played back at a high speed so that the amplitude of the reproduced signal is detected to find a no-signal portion positioned between two consecutive information or music pieces. When such a no-signal portion is detected, the fast playback is terminated to put the tape recorder in normal playback mode so that the desired piece of music or the like can be played back from the beginning thereof.
High-speed playback is actualized by depressing both a playback button and a fast forwarding or rewinding button simultaneously, and fast playback is continuously effected until a no-signal portion is detected. Therefore, music scanning mode consumes relatively large electrical power when compared with other operating modes. For this reason, music scanning function is provided to tape recorders which are powered by an a.c. line or large capacity cells. In other words, portable tape recorders of pocket size which are powered by small capacity cells, do not have such music scanning function.
Furthermore, in a cassette tape recorder having a mechanical manipulative buttons, the music scanning circuit or device requires a solenoid which automatically stops fast playback in response to a detection signal, and as a result, the music scanning circuit causes the increase in current consumed by the motor and the solenoid, while the solenoid control circuit is subjected to power source condition, in other words it is less tolerable to power source voltage drop.
This music scanning feature may be incorporated into a cassette tape recorder with a radio receiver having already many other functions. As a result it may become larger and larger in size and inconvenient for carrying. On the other hand, pocket size tape recorders are appreciated in the market for their portability.
However, since such portable cassette tape recorders use U-3 type cells, most of them are capable of only monaural recording and playback with headphone, and therefore portable cassette tape recorders with a music scanning circuit is not yet in the stage for practical application due to the above-mentioned power source conditions.
Recently, portable tape recorders with a radio receiver arranged such that a pocket size cassett tape recorder is detachably coupled with a radio receiver body, have appeared in the market. Although such detachably arranged tape recorder sets satisfy the requirements of portable and handy use or the tape recorder proper and also many functions, such combined or coupled sets have been provided to add various functions, such as playback with high power via speakers, recording of radio programs, and long-time recording by using a power source of large capacity in addition to the original function of the tape recorder proper.